We propose to continue our investigations of the structure and function of metal ions in metalloproteins by resonance Raman spectroscopy. In Raman spectroscopy an intense light source is employed to excite molecular vibrations. Subsequent analysis of the vibrational spectrum yields structural information. Resonance enhancement of Raman intensities can occur when the wavelength of light used to excite vibrational motions is within the electronic absorption band of a chromophore. In metalloproteins visible and near uv electronic transitions are due to the metalligand complex. The resonance Raman spectra obtained are, thus, specific for the metal ion and its immediate surrounding. We will ooncentrate on the application of this technique to the copper-containing metalloproteins. In previous studies of the copper protein, hemocyanin, we obtained the first direct evidence for the electronic structure of the copper-oxygen complex in this respiratory protein. We found that oxygen is bound as peroxide ion to a pair of cupric ions. We wish to complete this work by investigating other binuclear copper systems such as the oxygenated form of tyrosinase, molluscan hemocyanin, and model copper complexes. We will also carry out a systematic vibrational analysis of the "blue" copper proteins, ceruloplasmin, laccase, ascorbate oxidase, and azurin. We wish to obtain a more detailed understanding of the electronic and molecular site structures of the "blue" copper ions which are common to all of these proteins.